Automatic cochlear morphometry: intraindividual comparison of head CT vs carotid CT angiography, cervical spine, and paranasal sinus CT

Abstract Purpose In cochlear implantation, precise estimation of cochlear duct length (CDL) is essential for individualized electrode array selection. This study provides an intraindividual comparison of CDL measurements based on head CT vs cervical spine, carotid artery, and paranasal sinus imaging. Materials and methods For this retrospective investigation, automatic CDL measurements focused on the organ of Corti were performed in 459 patients (70.7 ± 17.8 years, 240 women), who underwent both head CT (120 kVp) and either cervical spine CT (Sn 150 kVp, 293 patients), carotid CT angiography (100 kVp, 133 patients), or paranasal sinus CT (Sn 100 kVp, 33 patients). Additionally, radiation dose and contrast-to-noise ratios were compared. Results Head CT (median 53.2 [interquartile range 49.6–56.8] mGy) was associated with a higher CTDI vol than cervical spine (16.3 [15.6–16.9] mGy), carotid artery (8.4 [8.2–8.7] mGy), and paranasal sinus CT (fixed 5.0 mGy; p < 0.001). CNR was higher in head CT (24.3 [21.4–27.1]) compared with carotid artery (17.9 [15.3–20.6]), cervical spine (12.3 [10.9–13.6]), and paranasal sinus CT (6.6 [5.7–7.4]; p < 0.001). No intraindividual CDL difference was ascertained for head CT (35.5 [34.4–36.5] mm) vs cervical spine (35.5 [34.3–36.5] mm; p = 0.371) and paranasal sinus CT (35.0 [34.3–36.1] mm; p = 0.112), whereas a small, but statistically significant difference, was found in the carotid artery sample (35.4 [34.4–36.4] mm; p < 0.001). Conclusion Despite lower CNR, CDL measurements based on cervical spine, carotid artery, and paranasal sinus CT yield comparable results to head CT imaging, suggesting potential for considerable dose reduction in cochlear morphometry. Key Points Question Do technically diverse low-dose protocols covering the temporal bone provide robust automatic CDL measurements in a large real-world patient sample? Findings In 459 patients, automatic cochlear morphometry from carotid angiography, cervical spine, and paranasal sinus CT was intraindividually comparable to head CT, despite lower CNR . Clinical relevance Validation of automatic CDL measurements from various routine CT protocols covering the temporal bone enables opportunistic cochlear implant planning with substantially reduced radiation exposure .